terrain guide

The terrain system's reference guide: a landscape composed in code as a procgen graph — the Raster the terrain.* ops pass along, the source → shape → mask → realize shape of a terrain graph, every op in the family, and a worked valley with a river.

Surfaced through guides { query: "terrain" } and guides { path: "systems/terrainSystem/documentation/terrain" } (likewise man). The content lives in guide.md; this README is the asset summary.

The hand-authoring face of the same system is the terrain toolbox (search_tools terrain), which carries its own README.